Constant torque adjustment for variable impedance devices



p 6. 1966 MASAOMI OSHIMA CONSTANT TORQUE ADJUSTMENT FOR VARIABLE IMPEDANCE DEVICES Filed Nov. 7, 1963 INVENTOR. N. Os h Lm a.

GLJwJJ-SB A TTORNE YS United States Patent 3,271,713 CONSTANT TORQUE ADJUSTMENT FOR VARIABLE IMFEDANCE DEVICES Masaorni Oshima, Yokohama-shi, Japan, assignor to Oshima Mason (30., Ltd, Yokohama-shit, Japan, a corporation of Japan Filed Nov. 7, 1963, Ser. No. 322,079 Claims priority, application Japan, Nov. 10, 1962, (utility model), 37/ 67,126 1 Claim. (Cl. 336-83) This invention relates to a high frequency coil device, and more particularly to a high frequency oscillation coil, an intermediate frequency transformer or the like having ferrite cores.

One object of this invention is to provide a high frequency coil device having a cylindrical ferrite core the adjustment of which can be made smoothly and accurately.

Another object of this invention is to provide a high frequency coil device having a cylindrical ferrite core which is screwed into a supporting portion in which the screwing torque is substantially constant all over the adjusting range of the ferrite core.

Other objects, features and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is an enlarged longitudinal sectional view of the high frequency coil device according to this invention;

FIGURE 2 is its cross sectional view along the line II-II of FIGURE 1;

FIGURE 3 is a graph, for explaining the relation between the position of a cylindrical ferrite core and torque for screwing the core of the device of this invention.

Referring to FIGURE 1, 1 is an insulated supporting plate made of a plastic insulating material such as phenol resin or the like. On the marginal side portions of the insulating support a pair of parallel pillars 2 and 3 are molded integrally therewith and a female screw 4 is formed on the inside of the pillars into which cylindrical ferrite core 9 such as described later is screwed. 11 shows an I-shaped ferrite core which is attached onto the supporting plate 1. On the I-shaped ferrite core is mounted a coil 12 toward which the cylindrical ferrite core 9 is adjusted.

In the process of molding such insulating support plate and confronting pillars by a conventional method, phenol resin is cast in a mold and taken off when it has not yet set or concreted. The reason that the cast is taken out from the mold when it has not yet become hard completely is mainly for the purpose of its mass production. As a result of such rough operation, the distance between pillars 2 and 3 is liable to become a little larger than the predetermined one and when the pillars 2 and 3 are pressed inwardly with fingers so as to correct it the distance is apt to become somewhat smaller than the predetermined one. It Will easily be seen that when a cylindrical ferrite core is screwed into screws formed on such pillars the rotary torque differs in accordance with its position as screwed. FIGURE 3,2 71,713 Patented Sept. 6, 1966 "ice 3 shows variations in the rotary torque obtained by experiments carried out by the applicant. In FIGURE 3, the torque is illustrated by the curve B which represents the torque-distance characteristics for separation of elements 2 and 3 less than the distance d, while the curve C represents the characteristics for distances greater than d, the abscissa representing the position of the cylindrical core and the ordinate the torque T (gr. cm). In the abscissa, the point S shows the position where the upper end face of the cylindrical core 9 and the upper surfaces of the pillars 2 and 3 are in the same plane and the point I the position where the center plane of the cylindrical core 9 substantially coincides with that of the pillars 2 and 3.

From a consideration of the foregoing, the advantage of the present invention is that a cylindrical core may be screwed between two pillars over a predetermined range with a substantially constant torque.

To this end, in this invention the pillars 2 and 3 are held and fixed with a predetermined distance d therebetween by a pair of confronting supporting plates 6 and 6 having curved edges 5 and 5 engaged with the outer end edges of the both pillars 2 and 3, and then they are covered with a metallic shield case 7. The plates 6 and 6 are arranged in the directions perpendicular with respect to the confronting pillars 2 and 3 and they are pressed inwardly by project-ions 8 formed on the inside of the case 7.

Therefore, the outer screw portion 10 of the cylindrical ferrite core 9 abuts against the inside of the supporting plates 5 and 5. The plates are made of a suitably soft synthetic resin or the like. When screwing the ferrite core 9 between the pillars 2 and 3 with the plates pressed from outside, the screw portion 10 of the ferrite core abuts against the inside of the plate, forming slight screw threads. It has been ascertained that after such screw threads have once been formed the torque for controlling the screwing of the cylindrical ferrite core is substantially constant irrespective of the position of the core.

Experiments show that the torque in the present invention can be illustrated by the curve A (FIG. 3), as compared with that in the conventional device. Therefore the ferrite core 9 presents substantially the same torque throughout the operation, namely, between the beginning and the end of the screwing, so that the adjustment of the core may be effected smoothly and accurately. Consequently, the high frequency coil of the present invention is very advantageous when employed as a high frequency oscillation coil or an intermediate frequency transformer or the like.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concept of this invention.

What is claimed is:

A high frequency coil device comprising an insulating supporting plate, an Lshaped core mounted on said insulating supporting plate, a coil carried by said core, a pair of parallel pillars Which extend upwardly from the marginal side portions of said insulating supporting plate and which have screws on the inside thereof, a cylindri- 3 4 cal ferrite core having outer screws meshing with said 7 References Cited by the Examiner screws of the pillars, a pair of opposed supporting plates, UNITED STATES PATENTS each having curved edges at the both ends thereof which respectively engage with the outer surfaces of said pillars 3O92796 5/1960 Maeda 336-136 X along the entire height thereof, thereby maintaining a 5 FOREIGN PATENTS predetermined distance between said pillars, and a me- 618,694 2/1949 Great Britain tallic shield case which covers said opposed supporting plates, said metallic shield case having projections which LARAMIE E. ASKIN, Primary Examiner.

engage and push said confronting supporting plates inwardly to press the same against the outer sides of said 10 JOHN BURNS ROBERT SCH'AEFER Examiners cylindrical ferrite core. C. TORRES, Assistant Examiner. 

